package com.tnt.sortingalgorithm; import java.util.Comparator; import java.util.Random; /** * 快速排序 * * @author Frankco * */ public class Quicksort { public static final Random RND = new Random(); /** * swap译为:交换 * @param array * @param i * @param j */ private static void swap(Object[] array, int i, int j) { Object tmp = array[i]; array[i] = array[j]; array[j] = tmp; } /** * Comparable和Comparator的区别? * Comparable适合用于将实体对象排序 * @param <E> * @param array * @param begin * @param end * @param cmp * @return */ private static <E> int partition(E[] array, int begin, int end, Comparator<? super E> cmp) { int index = begin + RND.nextInt(end - begin + 1); E pivot = array[index]; swap(array, index, end); for (int i = index = begin; i < end; ++i) { if (cmp.compare(array[i], pivot) <= 0) { swap(array, index++, i); } } swap(array, index, end); return (index); } /** * 递归 * @param <E> * @param array * @param begin * @param end * @param cmp */ private static <E> void qsort(E[] array, int begin, int end, Comparator<? super E> cmp) { if (end > begin) { int index = partition(array, begin, end, cmp); qsort(array, begin, index - 1, cmp); qsort(array, index + 1, end, cmp); } } public static <E> void sort(E[] array, Comparator<? super E> cmp) { qsort(array, 0, array.length - 1, cmp); } /** * 测试 * @param args */ public static void main(String[] args) { Integer[] arr = { 11, 52, 6, 8, 3, 4, 5, 7, 4, 6, 69, 8, 2, 5, 5, 2, 4, 2 }; sort(arr, new Comparator<Integer>() { public int compare(Integer a, Integer b) { if (a > b) return 1; else if (a < b) return -1; else return 0; } }); for (int i = 0; i < arr.length; i++) { System.out.println(arr[i]); } } }